1. Technical Field
The present disclosure relates to a test circuit of a circuit integrated on a wafer, such as an integrated circuit comprising at least one antenna of the embedded type.
2. Description of the Related Art
For the electric selection of devices carried out on wafer, i.e., the so called testing EWS (acronym of “Electrical-Wafer-Sorting”), a tester or ATE (acronym of “Automated Test Equipment”) is electrically connected to and executes measures on a wafer whereon there are electronic components to be tested or selected, particular chip. A terminal portion of a test system is schematically shown in FIG. 1A, globally indicated with 1.
The interface between the tester ATE 1A and a wafer 6 comprising a plurality of devices to be tested or selected, in particular the chips 7 (also indicated as integrated circuits or IC, acronym of “Integrated Circuit”) is a so called probe card 2, which is typically a board comprising a PCB (acronym of “Printed Circuit Board”) and a Probe Head 3 that includes different hundreds (or several times thousands) of probes 4 that electrically connect the tester ATE 1A to almost all the contact pads 8 of a chip 7 to be tested, as shown in greater detail schematically in FIG. 1B. In particular, each end portion or tip 9 of the probes 4 comes in contact with a pad 8 of the chip 7.
In general, the wafer 6 groups a plurality of chips 7 to be tested, and during the testing steps it is put on a support called a chuck 5, shown in the portion of the test system 1, and belonging to an apparatus also called a prober (not shown in the figure), this support being thus also indicated as prober chuck.
The number of pads 8 used for a determined testing can be smaller or equal to the total number of pads 8 of the chip 7 to be tested.
In a similar way, one goes further even if on the chips 7 having contact bumps instead of pads 8.
Before each chip 7 is encapsulated in a corresponding package, the testing of the chip 7 itself is typically executed, the chip being still on wafer 6, using the probes 4 that are connected directly to the pads 8, and that thus execute the so called probing of the pad 8 they come in contact with.
After the testing, the wafer 6 is cut and the chips 7 that have been tested and result operating are assembled in their package, ready for further process steps, which also may comprise testing steps in the package wherein they have been assembled.
Similarly to the testing on wafer, the tester ATE is typically able to execute a final test or FT (acronym of “Final Test”) of what is contained in the package comprising a given chip 7, electrically connecting to the connections of the package itself.
In the case of SiP systems (acronym of “System In Package”) there can be other situations, even very complex, further to the creation of electric connections between the various parts (chips, passive components, PCB, . . . ) of the system.
A generic electronic system or chip may be connected to the surrounding world through connections such as cabled channels (for example: cables, optical fibers, . . . ) or wireless channels, for example of the electromagnetic type. These connections allow to exchange information signals and/or to supply power to the same chips.
In case magnetic or electromagnetic signals are to be exchanged between an integrated circuit IC and at least another external system, the integrated circuit IC should have at least one receiver/transmitter inside, also called transceiver/transponder, connected to at least one antenna that can be embedded in the integrated circuit IC itself, as schematically shown in FIG. 2.
As illustrated, the integrated circuit IC 10 comprises a plurality of circuit portions 11, also indicated as Core 1 . . . Core 4, at least one of which, as illustrated Core 1, is connected to an antenna 12 through a transceiver/transponder 13.
Examples of integrated circuits IC equipped with an antenna are the RFID circuits (acronym of “Radio Frequency Identification Device”), Smart Cards, etc., that typically are low power integrated circuits (low power IC), that can be supplied and exchange information by using electromagnetic waves through wireless channels (and thus without contact or contactless) that use an electromagnetic coupling obtained through at least two antennas, of the type schematically shown in FIGS. 3A and 3B.
The RFID circuit, globally indicated with 15, comprises an antenna 17A, that can be for example a magnetic dipole or a hertzian dipole, which is connected to an integrated circuit IC 16A (as illustrated, a RFID/Smart card IC) in general by using bumps or wire bonds. The antenna 17A and the integrated circuit IC 16A are in general both contained in a single package. The antenna 17A is connected to the integrated circuit IC 16A, and this antenna 17A can be external to the circuit IC 16A, as indicated in FIG. 3A, or it can be embedded, and thus be part of an overall integrated circuit 16B, as indicated in FIG. 3B, thus having a circuit with an On-Chip Antenna (OCA), of which a portion is the integrated circuit IC 16A.
The RFID circuit 15 communicates, by means of the exchange of electromagnetic waves 18, to an external system, for example a reader 14 that comprises an antenna 17B and a reading system (RFID/Smart card Reader) 19, comprising at least one integrated circuit 16C, for example having characteristics being compatible and functionally specular with respect to the integrated circuit 16A.
The antenna 17A of FIG. 3B of the RFID circuit 15 can be of the magnetic type, in particular of the near field inductive type, and can be positioned around the integrated circuit IC 16A, with an increase of the area of the integrated circuit IC 16B itself and a consequent reduction of the total number of RFID circuits that can find place on a wafer. Alternatively, the antenna 17A can also be placed above the integrated circuit IC 16A in order to avoid such an area increase.
In particular, a known process for creating an antenna of the integrated or embedded type is a traditional diffusion process, that however uses additional masks and additional steps with respect to the wafer manufacturing process. Post processing methodologies are also able to create embedded antennas at lower costs.
In any case, the antennas of the embedded type, nowadays very used for RFID or Smart Cards, have a limited reach due to their sizes.
Antennas of the capacitive type are also known, that use the generic pad of an integrated circuit IC as an armature of a capacitor.